Conventionally, various sealing structures are applied to fishing reels such as spinning reels, double bearing reels, and electric reels so as to shut out foreign substances such as moisture and dust. Foreign substances tend to penetrate into fishing reels through the parts rotationally driven by handle operation or drive motors (drive shafts), and in particular through the bearings rotationally supporting the drive shafts. Penetration of foreign substances through such parts is unfavorable for maintaining smoothness of rotational operation of the handle. To overcome this problem, Japanese Patent Application Publication No. 2013-110 (the “'110 Publication”) discloses a fishing reel having a built-in bearing with a magnetic sealing mechanism wherein the bearing supporting a drive shaft rotationally driven by handle operation is sealed with a magnetic fluid. The bearing of the fishing reel disclosed in the '110 Publication has one-side magnetic sealing structure wherein a magnetic fluid is retained between an inner ring or an outer ring of the bearing and a retaining plate retaining a magnet.
When used in a harsh environment where seawater or dust tends to adhere or penetrate, even a fishing reel having a bearing disclosed in the '110 Publication cannot completely shut out seawater from the interior of the bearing. The seawater in the bearing may degrade smoothness of the bearing, making it impossible to maintain the smooth rotation for a long period. The '110 Publication discloses an embodiment wherein an O-ring is held on an opposite side to the retained magnetic fluid for sealing. However, the O-ring made of rubber is susceptible of degradation and damage. The fishing reel of this embodiment cannot maintain the stable sealing for a long period, and the increased number of parts complicates the build-in work.
Further, bearings, which are conventionally made of carbon steel or martensite-based stainless steel, may rust when used in a harsh environment where seawater tends to adhere or penetrate. Therefore, even if waterproofness for the interior of the bearing is simply increased, rusting from the inner ring, the outer ring, and the polar plate may cause sticking between these portions and the drive shaft or the housing (reel body) or cause improper operation of other drive components. Also, such a bearing is less corrosion resistive.